The preparation of HCEs is sufficiently well known from the prior art. More particularly, the applications EP 2018362 and WO 2013/026603 describe corresponding processes wherein the alcoholysis is effected in the liquid phase under pressure and ammonia formed is distilled off at pressures greater than 1 bar, or the HCE formed is removed via the gas phase.
However, the major problem with this prior art, or else in known processes in which said alcoholysis is effected in the gas phase, is that the isolated ammonia, when recycled into the hydrogen cyanide preparation process, results in considerable losses of catalyst activity even within a short time and makes it impossible to operate the plant economically.